It's clear very early on in this series that the heroes of the story are the two young men who are carrying out the terrorist bombings. You don't learn their reasons until nearly the end, but even in the first couple of episodes it's clear that they're not out to do major harm. They're careful to avoid deaths and minimize injuries, and even help to stop one of the bombings when things go wrong. I don't think the writers intended to condone the use of terrorism, but it's certainly not painted as the ultimate evil that we tend to think of in the modern world.
The evil in this series comes largely from governments. The main detective character is an outcast with the police force, having previously been demoted for pursuing the wrong powerful government official. Secret government programs played a large role in our young terrorists' background. The United States sends an armed contingent to "cooperate" with the police, effectively taking over and making things quite a bit worse. The corruption of authority is overwhelming, leading to those terrorist tactics.
Considering how short the series is (only 11 episodes, about 4 hours), I thought the characters were fairly well developed. There's time to get a good feel for the two young men, a girl that they befriend along the way, and their detective pursuer. Most of the other characters have little depth, but that's not really an issue since they don't get a lot of screen time anyhow. The limited length of the series means that it stays focused on the main characters and key story elements without much in the way of tangents, which I appreciated.
The production quality of Terror in Resonance is solid, if not particularly eye-catching. This isn't a series with a lot of flashy action sequences, but what action there was worked well. The voice actors did a solid job, the visuals were well done, and the music was great. (No surprise there, music by Yoko Kanno.)
I was very impressed with Terror in Resonance. It may be short, but that's not a drawback in a series that has a well-crafted story to tell. Definitely worth the watch.